The benefits of using a low dose Thallium-201 protocol with D-SPECT Cardiac Imaging System for myocardial perfusion studies

Objectives As cardiac imaging systems advance they are better able to: facilitate more strategic positioning of detectors, reduce imaging time, gate every study, obtain useful counts and reconstruct to produce quality, high resolution images. With these advancements, the option arises to adjust patient doses as to reduce cost and exposure while still yielding diagnostically useful information. Currently, most MPI protocols call for the use of Tc-99m Sestamibi or Tetrofosmin as the chief isotope. However, with the option of using low doses, there are advantages to a protocol that dictates using Thallium-201. The use of Tl-201 eliminates bowel and liver obstruction of the heart on the images as the method of uptake is via the sodium potassium pump used in the muscle movement of the left ventricle and does not clear through the hepatobilliary system. Although the half-life of Tl-201 is longer, it is also a lower energy than MIBI. This study will assess if there is a resolution and image quality difference between a full dose MIBI protocol and a low dose Tl-201 protocol when imaging using a D-SPECT system.

Methods Numerous studies from both a standard MIBI MPI protocol and a trial Tl-201 MPI protocol that dosed the patient 1-2mCi based on BMI were reviewed. All Tl-201 studies were obtained on a D-SPECT camera. The images were evaluated for bowel/liver obstruction and resolution quality.

Results Upon examination of the image sets, it was determined that there was a negligible difference in resolution quality between the protocols and there was little to no bowel/liver uptake on the rest and pharmaceutical stress images of the Tl-201 protocol.

Conclusions There are advantages to using a low dose Tl-201 protocol when imaging with an advanced cardiac imaging system, which includes a radiation dose reduction to the patient. These systems might, inversely, allow for full dose/half time protocols.